diff --git a/spring-boot-cli/src/main/java/org/springframework/boot/cli/app/SpringApplicationLauncher.java b/spring-boot-cli/src/main/java/org/springframework/boot/cli/app/SpringApplicationLauncher.java
index 09459da1d9..16faeba2fe 100644
--- a/spring-boot-cli/src/main/java/org/springframework/boot/cli/app/SpringApplicationLauncher.java
+++ b/spring-boot-cli/src/main/java/org/springframework/boot/cli/app/SpringApplicationLauncher.java
@@ -56,12 +56,12 @@ public class SpringApplicationLauncher {
 	 * @return The application's {@code ApplicationContext}
 	 * @throws Exception if the launch fails
 	 */
-	public Object launch(Object[] sources, String[] args) throws Exception {
+	public Object launch(Class<?>[] sources, String[] args) throws Exception {
 		Map<String, Object> defaultProperties = new HashMap<>();
 		defaultProperties.put("spring.groovy.template.check-template-location", "false");
 		Class<?> applicationClass = this.classLoader
 				.loadClass(getSpringApplicationClassName());
-		Constructor<?> constructor = applicationClass.getConstructor(Object[].class);
+		Constructor<?> constructor = applicationClass.getConstructor(Class[].class);
 		Object application = constructor.newInstance((Object) sources);
 		applicationClass.getMethod("setDefaultProperties", Map.class).invoke(application,
 				defaultProperties);
diff --git a/spring-boot-cli/src/main/java/org/springframework/boot/cli/archive/PackagedSpringApplicationLauncher.java b/spring-boot-cli/src/main/java/org/springframework/boot/cli/archive/PackagedSpringApplicationLauncher.java
index abc07ef8f2..33bc228f80 100644
--- a/spring-boot-cli/src/main/java/org/springframework/boot/cli/archive/PackagedSpringApplicationLauncher.java
+++ b/spring-boot-cli/src/main/java/org/springframework/boot/cli/archive/PackagedSpringApplicationLauncher.java
@@ -51,7 +51,7 @@ public final class PackagedSpringApplicationLauncher {
 		new SpringApplicationLauncher(classLoader).launch(getSources(classLoader), args);
 	}
 
-	private Object[] getSources(URLClassLoader classLoader) throws Exception {
+	private Class<?>[] getSources(URLClassLoader classLoader) throws Exception {
 		Enumeration<URL> urls = classLoader.getResources("META-INF/MANIFEST.MF");
 		while (urls.hasMoreElements()) {
 			URL url = urls.nextElement();
diff --git a/spring-boot-cli/src/main/java/org/springframework/boot/cli/command/run/SpringApplicationRunner.java b/spring-boot-cli/src/main/java/org/springframework/boot/cli/command/run/SpringApplicationRunner.java
index 49d4a5f072..470675d217 100644
--- a/spring-boot-cli/src/main/java/org/springframework/boot/cli/command/run/SpringApplicationRunner.java
+++ b/spring-boot-cli/src/main/java/org/springframework/boot/cli/command/run/SpringApplicationRunner.java
@@ -98,7 +98,7 @@ public class SpringApplicationRunner {
 		synchronized (this.monitor) {
 			try {
 				stop();
-				Object[] compiledSources = compile();
+				Class<?>[] compiledSources = compile();
 				monitorForChanges();
 				// Run in new thread to ensure that the context classloader is setup
 				this.runThread = new RunThread(compiledSources);
@@ -125,8 +125,8 @@ public class SpringApplicationRunner {
 		}
 	}
 
-	private Object[] compile() throws IOException {
-		Object[] compiledSources = this.compiler.compile(this.sources);
+	private Class<?>[] compile() throws IOException {
+		Class<?>[] compiledSources = this.compiler.compile(this.sources);
 		if (compiledSources.length == 0) {
 			throw new RuntimeException(
 					"No classes found in '" + Arrays.toString(this.sources) + "'");
@@ -148,7 +148,7 @@ public class SpringApplicationRunner {
 
 		private final Object monitor = new Object();
 
-		private final Object[] compiledSources;
+		private final Class<?>[] compiledSources;
 
 		private Object applicationContext;
 
@@ -156,10 +156,10 @@ public class SpringApplicationRunner {
 		 * Create a new {@link RunThread} instance.
 		 * @param compiledSources the sources to launch
 		 */
-		RunThread(Object... compiledSources) {
+		RunThread(Class<?>... compiledSources) {
 			super("runner-" + (runnerCounter++));
 			this.compiledSources = compiledSources;
-			if (compiledSources.length != 0 && compiledSources[0] instanceof Class) {
+			if (compiledSources.length != 0) {
 				setContextClassLoader(((Class<?>) compiledSources[0]).getClassLoader());
 			}
 			setDaemon(true);
diff --git a/spring-boot-cli/src/test/java/org/springframework/boot/cli/app/SpringApplicationLauncherTests.java b/spring-boot-cli/src/test/java/org/springframework/boot/cli/app/SpringApplicationLauncherTests.java
index 654c8b1cea..f2ca3d8845 100644
--- a/spring-boot-cli/src/test/java/org/springframework/boot/cli/app/SpringApplicationLauncherTests.java
+++ b/spring-boot-cli/src/test/java/org/springframework/boot/cli/app/SpringApplicationLauncherTests.java
@@ -73,7 +73,7 @@ public class SpringApplicationLauncherTests {
 	public void sourcesDefaultPropertiesAndArgsAreUsedToLaunch() throws Exception {
 		System.setProperty("spring.application.class.name",
 				TestSpringApplication.class.getName());
-		Object[] sources = new Object[0];
+		Class<?>[] sources = new Class<?>[0];
 		String[] args = new String[0];
 		new SpringApplicationLauncher(getClass().getClassLoader()).launch(sources, args);
 
@@ -88,7 +88,7 @@ public class SpringApplicationLauncherTests {
 	private Set<String> launch() {
 		TestClassLoader classLoader = new TestClassLoader(getClass().getClassLoader());
 		try {
-			new TestSpringApplicationLauncher(classLoader).launch(new Object[0],
+			new TestSpringApplicationLauncher(classLoader).launch(new Class<?>[0],
 					new String[0]);
 		}
 		catch (Exception ex) {
@@ -129,7 +129,7 @@ public class SpringApplicationLauncherTests {
 
 		private static String[] args;
 
-		public TestSpringApplication(Object[] sources) {
+		public TestSpringApplication(Class<?>[] sources) {
 			TestSpringApplication.sources = sources;
 		}
 
diff --git a/spring-boot-docs/src/main/asciidoc/using-spring-boot.adoc b/spring-boot-docs/src/main/asciidoc/using-spring-boot.adoc
index c1afe0d48d..2f49632d07 100644
--- a/spring-boot-docs/src/main/asciidoc/using-spring-boot.adoc
+++ b/spring-boot-docs/src/main/asciidoc/using-spring-boot.adoc
@@ -398,10 +398,10 @@ The `Application.java` file would declare the `main` method, along with the basi
 
 [[using-boot-configuration-classes]]
 == Configuration classes
-Spring Boot favors Java-based configuration. Although it is possible to call
-`SpringApplication.run()` with an XML source, we generally recommend that your primary
-source is a `@Configuration` class. Usually the class that defines the `main` method
-is also a good candidate as the primary `@Configuration`.
+Spring Boot favors Java-based configuration. Although it is possible to use
+`SpringApplication` with an XML sources, we generally recommend that your primary
+source is a single `@Configuration` class. Usually the class that defines the `main`
+method is also a good candidate as the primary `@Configuration`.
 
 TIP: Many Spring configuration examples have been published on the Internet that use XML
 configuration. Always try to use the equivalent Java-based configuration if possible.
diff --git a/spring-boot-samples/spring-boot-sample-xml/src/main/java/sample/xml/SampleSpringXmlApplication.java b/spring-boot-samples/spring-boot-sample-xml/src/main/java/sample/xml/SampleSpringXmlApplication.java
index c07d9563eb..435b2d9952 100644
--- a/spring-boot-samples/spring-boot-sample-xml/src/main/java/sample/xml/SampleSpringXmlApplication.java
+++ b/spring-boot-samples/spring-boot-sample-xml/src/main/java/sample/xml/SampleSpringXmlApplication.java
@@ -16,6 +16,8 @@
 
 package sample.xml;
 
+import java.util.Collections;
+
 import sample.xml.service.HelloWorldService;
 
 import org.springframework.beans.factory.annotation.Autowired;
@@ -24,6 +26,8 @@ import org.springframework.boot.SpringApplication;
 
 public class SampleSpringXmlApplication implements CommandLineRunner {
 
+	private static final String CONTEXT_XML = "classpath:/META-INF/application-context.xml";
+
 	@Autowired
 	private HelloWorldService helloWorldService;
 
@@ -33,7 +37,9 @@ public class SampleSpringXmlApplication implements CommandLineRunner {
 	}
 
 	public static void main(String[] args) throws Exception {
-		SpringApplication.run("classpath:/META-INF/application-context.xml", args);
+		SpringApplication application = new SpringApplication();
+		application.setSources(Collections.singleton(CONTEXT_XML));
+		application.run(args);
 	}
 
 }
diff --git a/spring-boot-test/src/main/java/org/springframework/boot/test/context/SpringBootContextLoader.java b/spring-boot-test/src/main/java/org/springframework/boot/test/context/SpringBootContextLoader.java
index 7f0f89d664..24e6dcd452 100644
--- a/spring-boot-test/src/main/java/org/springframework/boot/test/context/SpringBootContextLoader.java
+++ b/spring-boot-test/src/main/java/org/springframework/boot/test/context/SpringBootContextLoader.java
@@ -91,9 +91,20 @@ public class SpringBootContextLoader extends AbstractContextLoader {
 	@Override
 	public ApplicationContext loadContext(MergedContextConfiguration config)
 			throws Exception {
+		Class<?>[] configClasses = config.getClasses();
+		String[] configLocations = config.getLocations();
+		Assert.state(
+				!ObjectUtils.isEmpty(configClasses)
+						|| !ObjectUtils.isEmpty(configLocations),
+				"No configuration classes "
+						+ "or locations found in @SpringApplicationConfiguration. "
+						+ "For default configuration detection to work you need "
+						+ "Spring 4.0.3 or better (found " + SpringVersion.getVersion()
+						+ ").");
 		SpringApplication application = getSpringApplication();
 		application.setMainApplicationClass(config.getTestClass());
-		application.setSources(getSources(config));
+		application.addPrimarySources(Arrays.asList(configClasses));
+		application.getSources().addAll(Arrays.asList(configLocations));
 		ConfigurableEnvironment environment = new StandardEnvironment();
 		if (!ObjectUtils.isEmpty(config.getActiveProfiles())) {
 			setActiveProfiles(environment, config.getActiveProfiles());
@@ -137,17 +148,6 @@ public class SpringBootContextLoader extends AbstractContextLoader {
 		return new SpringApplication();
 	}
 
-	private Set<Object> getSources(MergedContextConfiguration mergedConfig) {
-		Set<Object> sources = new LinkedHashSet<>();
-		sources.addAll(Arrays.asList(mergedConfig.getClasses()));
-		sources.addAll(Arrays.asList(mergedConfig.getLocations()));
-		Assert.state(!sources.isEmpty(), "No configuration classes "
-				+ "or locations found in @SpringApplicationConfiguration. "
-				+ "For default configuration detection to work you need "
-				+ "Spring 4.0.3 or better (found " + SpringVersion.getVersion() + ").");
-		return sources;
-	}
-
 	private void setActiveProfiles(ConfigurableEnvironment environment,
 			String[] profiles) {
 		EnvironmentTestUtils.addEnvironment(environment, "spring.profiles.active="
diff --git a/spring-boot/src/main/java/org/springframework/boot/SpringApplication.java b/spring-boot/src/main/java/org/springframework/boot/SpringApplication.java
index 6328c5f606..e0891750be 100644
--- a/spring-boot/src/main/java/org/springframework/boot/SpringApplication.java
+++ b/spring-boot/src/main/java/org/springframework/boot/SpringApplication.java
@@ -65,7 +65,6 @@ import org.springframework.core.env.PropertySource;
 import org.springframework.core.env.SimpleCommandLinePropertySource;
 import org.springframework.core.env.StandardEnvironment;
 import org.springframework.core.io.DefaultResourceLoader;
-import org.springframework.core.io.Resource;
 import org.springframework.core.io.ResourceLoader;
 import org.springframework.core.io.support.SpringFactoriesLoader;
 import org.springframework.util.Assert;
@@ -92,7 +91,7 @@ import org.springframework.web.context.support.StandardServletEnvironment;
  * <li>Trigger any {@link CommandLineRunner} beans</li>
  * </ul>
  *
- * In most circumstances the static {@link #run(Object, String[])} method can be called
+ * In most circumstances the static {@link #run(Class, String[])} method can be called
  * directly from your {@literal main} method to bootstrap your application:
  *
  * <pre class="code">
@@ -122,18 +121,13 @@ import org.springframework.web.context.support.StandardServletEnvironment;
  *
  * {@link SpringApplication}s can read beans from a variety of different sources. It is
  * generally recommended that a single {@code @Configuration} class is used to bootstrap
- * your application, however, any of the following sources can also be used:
- *
+ * your application, however, you may also set {@link #getSources() sources} from:
  * <ul>
- * <li>{@link Class} - A Java class to be loaded by {@link AnnotatedBeanDefinitionReader}
- * </li>
- * <li>{@link Resource} - An XML resource to be loaded by {@link XmlBeanDefinitionReader},
- * or a groovy script to be loaded by {@link GroovyBeanDefinitionReader}</li>
- * <li>{@link Package} - A Java package to be scanned by
- * {@link ClassPathBeanDefinitionScanner}</li>
- * <li>{@link CharSequence} - A class name, resource handle or package name to loaded as
- * appropriate. If the {@link CharSequence} cannot be resolved to class and does not
- * resolve to a {@link Resource} that exists it will be considered a {@link Package}.</li>
+ * <li>The fully qualified class name to be loaded by
+ * {@link AnnotatedBeanDefinitionReader}</li>
+ * <li>The location of an XML resource to be loaded by {@link XmlBeanDefinitionReader}, or
+ * a groovy script to be loaded by {@link GroovyBeanDefinitionReader}</li>
+ * <li>The name of a package to be scanned by {@link ClassPathBeanDefinitionScanner}</li>
  * </ul>
  *
  * Configuration properties are also bound to the {@link SpringApplication}. This makes it
@@ -152,9 +146,9 @@ import org.springframework.web.context.support.StandardServletEnvironment;
  * @author Michael Simons
  * @author Madhura Bhave
  * @author Brian Clozel
- * @see #run(Object, String[])
- * @see #run(Object[], String[])
- * @see #SpringApplication(Object...)
+ * @see #run(Class, String[])
+ * @see #run(Class[], String[])
+ * @see #SpringApplication(Class...)
  */
 public class SpringApplication {
 
@@ -214,9 +208,9 @@ public class SpringApplication {
 
 	private static final Log logger = LogFactory.getLog(SpringApplication.class);
 
-	private Set<Object> primarySources;
+	private Set<Class<?>> primarySources;
 
-	private Set<Object> sources = new LinkedHashSet<>();
+	private Set<String> sources = new LinkedHashSet<>();
 
 	private Class<?> mainApplicationClass;
 
@@ -256,12 +250,12 @@ public class SpringApplication {
 	 * documentation for details. The instance can be customized before calling
 	 * {@link #run(String...)}.
 	 * @param primarySources the primary bean sources
-	 * @see #run(Object, String[])
-	 * @see #SpringApplication(ResourceLoader, Object...)
+	 * @see #run(Class, String[])
+	 * @see #SpringApplication(ResourceLoader, Class...)
 	 * @see #setSources(Set)
 	 */
-	public SpringApplication(Object... primarySources) {
-		initialize(primarySources);
+	public SpringApplication(Class<?>... primarySources) {
+		this(null, primarySources);
 	}
 
 	/**
@@ -271,17 +265,12 @@ public class SpringApplication {
 	 * {@link #run(String...)}.
 	 * @param resourceLoader the resource loader to use
 	 * @param primarySources the primary bean sources
-	 * @see #run(Object, String[])
-	 * @see #SpringApplication(ResourceLoader, Object...)
+	 * @see #run(Class, String[])
 	 * @see #setSources(Set)
 	 */
-	public SpringApplication(ResourceLoader resourceLoader, Object... primarySources) {
-		this.resourceLoader = resourceLoader;
-		initialize(primarySources);
-	}
-
 	@SuppressWarnings({ "unchecked", "rawtypes" })
-	private void initialize(Object[] primarySources) {
+	public SpringApplication(ResourceLoader resourceLoader, Class<?>... primarySources) {
+		this.resourceLoader = resourceLoader;
 		Assert.notNull(primarySources, "PrimarySources must not be null");
 		this.primarySources = new LinkedHashSet<>(Arrays.asList(primarySources));
 		this.webApplicationType = deduceWebApplication();
@@ -1131,12 +1120,12 @@ public class SpringApplication {
 	 * should consider using {@link #getSources()}/{@link #setSources(Set)} rather than
 	 * this calling method.
 	 * @param additionalPrimarySources the additional primary sources to add
-	 * @see #SpringApplication(Object...)
+	 * @see #SpringApplication(Class...)
 	 * @see #getSources()
 	 * @see #setSources(Set)
 	 * @see #getAllSources()
 	 */
-	public void addPrimarySources(Collection<Object> additionalPrimarySources) {
+	public void addPrimarySources(Collection<Class<?>> additionalPrimarySources) {
 		this.primarySources.addAll(additionalPrimarySources);
 	}
 
@@ -1147,24 +1136,24 @@ public class SpringApplication {
 	 * Sources set here will be used in addition to any primary sources set in the
 	 * constructor.
 	 * @return the application sources.
-	 * @see #SpringApplication(Object...)
+	 * @see #SpringApplication(Class...)
 	 * @see #getAllSources()
 	 */
-	public Set<Object> getSources() {
+	public Set<String> getSources() {
 		return this.sources;
 	}
 
 	/**
 	 * Set additional sources that will be used to create an ApplicationContext. A source
-	 * can be: a class, class name, package, package name, or an XML resource location.
+	 * can be: a class name, package name, or an XML resource location.
 	 * <p>
 	 * Sources set here will be used in addition to any primary sources set in the
 	 * constructor.
 	 * @param sources the application sources to set
-	 * @see #SpringApplication(Object...)
+	 * @see #SpringApplication(Class...)
 	 * @see #getAllSources()
 	 */
-	public void setSources(Set<Object> sources) {
+	public void setSources(Set<String> sources) {
 		Assert.notNull(sources, "Sources must not be null");
 		this.sources = new LinkedHashSet<>(sources);
 	}
@@ -1284,9 +1273,9 @@ public class SpringApplication {
 	 * @param args the application arguments (usually passed from a Java main method)
 	 * @return the running {@link ApplicationContext}
 	 */
-	public static ConfigurableApplicationContext run(Object primarySource,
+	public static ConfigurableApplicationContext run(Class<?> primarySource,
 			String... args) {
-		return run(new Object[] { primarySource }, args);
+		return run(new Class<?>[] { primarySource }, args);
 	}
 
 	/**
@@ -1296,7 +1285,7 @@ public class SpringApplication {
 	 * @param args the application arguments (usually passed from a Java main method)
 	 * @return the running {@link ApplicationContext}
 	 */
-	public static ConfigurableApplicationContext run(Object[] primarySources,
+	public static ConfigurableApplicationContext run(Class<?>[] primarySources,
 			String[] args) {
 		return new SpringApplication(primarySources).run(args);
 	}
@@ -1307,14 +1296,14 @@ public class SpringApplication {
 	 * argument.
 	 * <p>
 	 * Most developers will want to define their own main method and call the
-	 * {@link #run(Object, String...) run} method instead.
+	 * {@link #run(Class, String...) run} method instead.
 	 * @param args command line arguments
 	 * @throws Exception if the application cannot be started
-	 * @see SpringApplication#run(Object[], String[])
-	 * @see SpringApplication#run(Object, String...)
+	 * @see SpringApplication#run(Class[], String[])
+	 * @see SpringApplication#run(Class, String...)
 	 */
 	public static void main(String[] args) throws Exception {
-		SpringApplication.run(new Object[0], args);
+		SpringApplication.run(new Class<?>[0], args);
 	}
 
 	/**
diff --git a/spring-boot/src/main/java/org/springframework/boot/builder/SpringApplicationBuilder.java b/spring-boot/src/main/java/org/springframework/boot/builder/SpringApplicationBuilder.java
index da65d8f071..e2f6963b9d 100644
--- a/spring-boot/src/main/java/org/springframework/boot/builder/SpringApplicationBuilder.java
+++ b/spring-boot/src/main/java/org/springframework/boot/builder/SpringApplicationBuilder.java
@@ -73,7 +73,7 @@ public class SpringApplicationBuilder {
 
 	private final AtomicBoolean running = new AtomicBoolean(false);
 
-	private final Set<Object> sources = new LinkedHashSet<>();
+	private final Set<Class<?>> sources = new LinkedHashSet<>();
 
 	private final Map<String, Object> defaultProperties = new LinkedHashMap<>();
 
@@ -85,7 +85,7 @@ public class SpringApplicationBuilder {
 
 	private boolean configuredAsChild = false;
 
-	public SpringApplicationBuilder(Object... sources) {
+	public SpringApplicationBuilder(Class<?>... sources) {
 		this.application = createSpringApplication(sources);
 	}
 
@@ -97,7 +97,7 @@ public class SpringApplicationBuilder {
 	 * @return The {@link org.springframework.boot.SpringApplication} instance
 	 * @since 1.1.0
 	 */
-	protected SpringApplication createSpringApplication(Object... sources) {
+	protected SpringApplication createSpringApplication(Class<?>... sources) {
 		return new SpringApplication(sources);
 	}
 
@@ -176,7 +176,7 @@ public class SpringApplicationBuilder {
 	 * @param sources the sources for the application (Spring configuration)
 	 * @return the child application builder
 	 */
-	public SpringApplicationBuilder child(Object... sources) {
+	public SpringApplicationBuilder child(Class<?>... sources) {
 		SpringApplicationBuilder child = new SpringApplicationBuilder();
 		child.sources(sources);
 
@@ -205,7 +205,7 @@ public class SpringApplicationBuilder {
 	 * @param sources the sources for the application (Spring configuration)
 	 * @return the parent builder
 	 */
-	public SpringApplicationBuilder parent(Object... sources) {
+	public SpringApplicationBuilder parent(Class<?>... sources) {
 		if (this.parent == null) {
 			this.parent = new SpringApplicationBuilder(sources).web(false)
 					.properties(this.defaultProperties).environment(this.environment);
@@ -245,7 +245,7 @@ public class SpringApplicationBuilder {
 	 * @param sources the sources for the application (Spring configuration)
 	 * @return the new sibling builder
 	 */
-	public SpringApplicationBuilder sibling(Object... sources) {
+	public SpringApplicationBuilder sibling(Class<?>... sources) {
 		return runAndExtractParent().child(sources);
 	}
 
@@ -258,7 +258,7 @@ public class SpringApplicationBuilder {
 	 * parent
 	 * @return the new sibling builder
 	 */
-	public SpringApplicationBuilder sibling(Object[] sources, String... args) {
+	public SpringApplicationBuilder sibling(Class<?>[] sources, String... args) {
 		return runAndExtractParent(args).child(sources);
 	}
 
@@ -273,23 +273,13 @@ public class SpringApplicationBuilder {
 		return this;
 	}
 
-	/**
-	 * Add more sources to use in this application.
-	 * @param sources the sources to add
-	 * @return the current builder
-	 */
-	public SpringApplicationBuilder sources(Object... sources) {
-		this.sources.addAll(new LinkedHashSet<>(Arrays.asList(sources)));
-		return this;
-	}
-
 	/**
 	 * Add more sources (configuration classes and components) to this application.
 	 * @param sources the sources to add
 	 * @return the current builder
 	 */
 	public SpringApplicationBuilder sources(Class<?>... sources) {
-		this.sources.addAll(new LinkedHashSet<Object>(Arrays.asList(sources)));
+		this.sources.addAll(new LinkedHashSet<>(Arrays.asList(sources)));
 		return this;
 	}
 
diff --git a/spring-boot/src/main/java/org/springframework/boot/web/servlet/support/SpringBootServletInitializer.java b/spring-boot/src/main/java/org/springframework/boot/web/servlet/support/SpringBootServletInitializer.java
index a51b053e5e..a1b2eda77e 100644
--- a/spring-boot/src/main/java/org/springframework/boot/web/servlet/support/SpringBootServletInitializer.java
+++ b/spring-boot/src/main/java/org/springframework/boot/web/servlet/support/SpringBootServletInitializer.java
@@ -47,7 +47,7 @@ import org.springframework.web.context.WebApplicationContext;
  * <p>
  * To configure the application either override the
  * {@link #configure(SpringApplicationBuilder)} method (calling
- * {@link SpringApplicationBuilder#sources(Object...)}) or make the initializer itself a
+ * {@link SpringApplicationBuilder#sources(Class...)}) or make the initializer itself a
  * {@code @Configuration}. If you are using {@link SpringBootServletInitializer} in
  * combination with other {@link WebApplicationInitializer WebApplicationInitializers} you
  * might also want to add an {@code @Ordered} annotation to configure a specific startup
@@ -126,7 +126,8 @@ public abstract class SpringBootServletInitializer implements WebApplicationInit
 						+ "configure method or add an @Configuration annotation");
 		// Ensure error pages are registered
 		if (this.registerErrorPageFilter) {
-			application.getSources().add(ErrorPageFilterConfiguration.class);
+			application.addPrimarySources(
+					Collections.singleton(ErrorPageFilterConfiguration.class));
 		}
 		return run(application);
 	}
diff --git a/spring-boot/src/test/java/org/springframework/boot/OverrideSourcesTests.java b/spring-boot/src/test/java/org/springframework/boot/OverrideSourcesTests.java
index 7f0e0f7694..8af43838da 100644
--- a/spring-boot/src/test/java/org/springframework/boot/OverrideSourcesTests.java
+++ b/spring-boot/src/test/java/org/springframework/boot/OverrideSourcesTests.java
@@ -46,7 +46,7 @@ public class OverrideSourcesTests {
 
 	@Test
 	public void beanInjectedToMainConfiguration() {
-		this.context = SpringApplication.run(new Object[] { MainConfiguration.class },
+		this.context = SpringApplication.run(new Class<?>[] { MainConfiguration.class },
 				new String[] { "--spring.main.web_environment=false" });
 		assertThat(this.context.getBean(Service.class).bean.name).isEqualTo("foo");
 	}
@@ -54,7 +54,7 @@ public class OverrideSourcesTests {
 	@Test
 	public void primaryBeanInjectedProvingSourcesNotOverridden() {
 		this.context = SpringApplication.run(
-				new Object[] { MainConfiguration.class, TestConfiguration.class },
+				new Class<?>[] { MainConfiguration.class, TestConfiguration.class },
 				new String[] { "--spring.main.web_environment=false",
 						"--spring.main.sources=org.springframework.boot.OverrideSourcesTests.MainConfiguration" });
 		assertThat(this.context.getBean(Service.class).bean.name).isEqualTo("bar");
diff --git a/spring-boot/src/test/java/org/springframework/boot/SpringApplicationTests.java b/spring-boot/src/test/java/org/springframework/boot/SpringApplicationTests.java
index 0fc86064ea..af47c4cc69 100644
--- a/spring-boot/src/test/java/org/springframework/boot/SpringApplicationTests.java
+++ b/spring-boot/src/test/java/org/springframework/boot/SpringApplicationTests.java
@@ -160,7 +160,7 @@ public class SpringApplicationTests {
 	public void sourcesMustNotBeNull() throws Exception {
 		this.thrown.expect(IllegalArgumentException.class);
 		this.thrown.expectMessage("PrimarySources must not be null");
-		new SpringApplication((Object[]) null).run();
+		new SpringApplication((Class<?>[]) null).run();
 	}
 
 	@Test
@@ -576,20 +576,22 @@ public class SpringApplicationTests {
 
 	@Test
 	public void loadSources() throws Exception {
-		Object[] sources = { ExampleConfig.class, "a", TestCommandLineRunner.class };
+		Class<?>[] sources = { ExampleConfig.class, TestCommandLineRunner.class };
 		TestSpringApplication application = new TestSpringApplication(sources);
+		application.getSources().add("a");
 		application.setWebApplicationType(WebApplicationType.NONE);
 		application.setUseMockLoader(true);
 		this.context = application.run();
 		Set<Object> allSources = application.getAllSources();
-		assertThat(allSources.toArray()).isEqualTo(sources);
+		assertThat(allSources).contains(ExampleConfig.class, TestCommandLineRunner.class,
+				"a");
 	}
 
 	@Test
 	public void wildcardSources() {
-		Object[] sources = {
-				"classpath:org/springframework/boot/sample-${sample.app.test.prop}.xml" };
-		TestSpringApplication application = new TestSpringApplication(sources);
+		TestSpringApplication application = new TestSpringApplication();
+		application.getSources().add(
+				"classpath:org/springframework/boot/sample-${sample.app.test.prop}.xml");
 		application.setWebApplicationType(WebApplicationType.NONE);
 		this.context = application.run();
 	}
@@ -603,7 +605,7 @@ public class SpringApplicationTests {
 	@Test
 	public void runComponents() throws Exception {
 		this.context = SpringApplication.run(
-				new Object[] { ExampleWebConfig.class, Object.class }, new String[0]);
+				new Class<?>[] { ExampleWebConfig.class, Object.class }, new String[0]);
 		assertThat(this.context).isNotNull();
 	}
 
@@ -970,12 +972,12 @@ public class SpringApplicationTests {
 
 		private Banner.Mode bannerMode;
 
-		TestSpringApplication(Object... sources) {
-			super(sources);
+		TestSpringApplication(Class<?>... primarySources) {
+			super(primarySources);
 		}
 
-		TestSpringApplication(ResourceLoader resourceLoader, Object... sources) {
-			super(resourceLoader, sources);
+		TestSpringApplication(ResourceLoader resourceLoader, Class<?>... primarySources) {
+			super(resourceLoader, primarySources);
 		}
 
 		public void setUseMockLoader(boolean useMockLoader) {